Tool for plating resin molded body and method for plating resin molded body using the same

ABSTRACT

An object of the present invention is to provide a plating tool which avoids plating deposition on the tool itself in plating of a resin molded body, and therefore, also eliminates the need to exchange the plating tool. The object is achieved by a tool for plating a resin molded body, wherein a surface of a plating tool having an insulation coating part is coated with a plasticizer, and a method for plating a resin molded body using the tool.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a tool for plating a resin molded body for holding the resin molded body during an operation of plating the resin molded body, and a method for plating a resin molded body using the tool.

Background Art

Conventionally, in the case where a surface of a resin molded body of an acrylonitrile-butadiene-styrene (ABS) resin, a polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) resin, or the like is plated, it is known to perform an etching treatment for roughening the surface of the resin molded body with a mixed liquid of chromic acid and sulfuric acid before a plating treatment in order to increase the adhesion between the resin molded body and a plating film.

However, a large amount of harmful hexavalent chromium is contained in the above-mentioned etching liquid, and the etching liquid has an adverse effect on the operation environment. Further, in order to safely treat the waste water thereof, a complicated treatment in which harmful hexavalent chromium is reduced to trivalent chromium, and then, the trivalent chromium is precipitated by neutralization, or the like is needed. In this treatment, the operation is performed at a high temperature of 60° C. or higher using harmful hexavalent chromium, and therefore, the operation environment is poor, and also there is a problem that it is necessary to pay attention also to the treatment of the waste water thereof.

In light of these problems, it is desired to provide an etchant as a substitute for the mixed liquid of chromic acid and sulfuric acid, and, for example, a plating process free from chromic acid etching in which a treatment is performed with an etchant using a permanganate in place of these etchants and plating is performed has been reported (see JP-A-52-124434 (Patent Document 1) and Japanese Patent No. 5177426 (Patent Document 2)).

However, in the above process, plating on a surface of a plastic can be performed, but a catalytic metal is adsorbed also on a coating surface of a tool, and therefore, there is a problem that plating is likely to be deposited on the surface of the tool as well as on the surface of the plastic by the subsequent plating step.

In etching with the mixed liquid of chromic acid and sulfuric acid used conventionally, a small amount of hexavalent chromium remains in an insulation coating portion of a plating tool in an etching treatment step, and this serves as a catalyst poison, and even in the case where an electroless plating catalyst remains in the insulation coating portion of the tool, electroless plating is prevented from depositing on the surface of the tool. Due to this, even in the case where electroplating is performed sequentially, electroplating is not deposited on the plating tool, and electroless plating and electroplating can be performed sequentially.

On the other hand, in the case where an etching treatment liquid containing a permanganate as a main component is used, a component to serve as a catalyst poison is not contained in the etching treatment liquid. Therefore, when an electroless plating catalyst is adhered to the insulation coating portion of the plating tool, electroless plating is deposited on this portion. Due to this, it is necessary to exchange the tool when the process is shifted from electroless plating to electroplating, and therefore, there is a problem that the workability is very poor.

In view of this, several methods for suppressing plating deposition on a tool have been reported (JP-A-2009-30151 (Patent Document 3)); however, in each method, a special and expensive material is needed, for example, a fluororesin or the like is used for a tool coating part, resulting in high cost, and therefore, such a method is not practical.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a plating tool which avoids plating deposition on the tool itself while using a general-purpose tool which has been used so far in plating of a resin molded body, and therefore, also eliminates the need to exchange the plating tool.

As a result of intensive studies for achieving the above object, the present inventors found that the above object can be achieved by coating a surface of a plating tool having an insulation coating part which is usually used in plating of a resin molded body with a plasticizer, and thus, completed the present invention.

That is, the present invention is directed to a tool for plating a resin molded body, wherein a surface of a plating tool having an insulation coating part is coated with a plasticizer.

Further, the present invention is directed to a method for producing a tool for plating a resin molded body, including treating a surface of a plating tool having an insulation coating part with a plasticizer so as to coat the surface of the plating tool having an insulation coating part with the plasticizer.

Still further, the present invention is directed to a method for plating a resin molded body, including using the tool for plating a resin molded body in plating of the resin molded body.

According to the tool for plating a resin molded body of the present invention, plating deposition on the tool itself does not occur in plating of a resin molded body, and therefore, the plating tool does not need to be exchanged.

Therefore, the tool for plating a resin molded body of the present invention can be favorably used in plating of a resin molded body.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A tool for plating a resin molded body of the present invention (hereinafter referred to as “tool of the present invention”) is configured such that a surface of a plating tool having an insulation coating part which is usually used in plating of a resin molded body is coated with a plasticizer.

The plating tool having an insulation coating part which is usually used in plating of a resin molded body (hereinafter referred to as “usual tool”) includes an electricity conducting part, on which the resin molded body is hung and which is provided for conducting electricity to the resin molded body, and an insulation coating part formed by coating a region where plating is not desired to be deposited in the electricity conducting part with an insulator. Incidentally, the shape of the tool is not particularly limited.

The electricity conducting part of the usual tool is formed of, for example, a metal capable of conducting electricity, such as SUS or copper. Further, the insulation coating part is formed of an insulator, for example, a fluororesin, a silicone resin, or a thermoplastic resin. Among these insulators, thermoplastic resins are preferred, and among these, vinyl chloride is more preferred. The coating of the electricity conducting part with such an insulator can be performed by a conventional method. Further, these insulators may contain a plasticizer.

In order to coat the surface of the usual tool with a plasticizer, the surface of the usual tool only need to be treated with the plasticizer.

The treatment method is not particularly limited, but examples thereof include a method in which a process for immersing the usual tool in a solution containing a plasticizer, a process for applying a solution containing a plasticizer to the usual tool, or the like is performed, and thereafter, the usual tool is dried or fired, for example, whereby the surface of the usual tool is coated with the plasticizer. Incidentally, the plasticizer does not have any influence on the electricity conducting part; however, when a degreasing treatment is performed after coating, the plasticizer on the electricity conducting part can be removed.

The plasticizer used here is not particularly limited; however, ester compounds synthesized from an acid and an alcohol are preferred, and phthalate esters, adipate esters, trimellitate esters, phosphate esters, citrate esters, sebacate esters, azelate esters, maleate esters, and benzoate esters are more preferred. It is only necessary to contain at least one plasticizer among these plasticizers.

The concentration of such a plasticizer is not particularly limited, and for example, a commercially available stock solution can be used as it is. Further, the temperature of such a plasticizer is not particularly limited, and is, for example, a normal temperature.

The conditions for drying or firing vary depending on the type or concentration of the plasticizer, and therefore are not particularly limited, and may be any condition except for the conditions in which, for example, the plasticizer is volatilized and thus, coating cannot be performed. General examples of such conditions include about one day at a normal temperature in the case of drying, and about 20 minutes at 160° C. in the case of firing. Further, drying or firing may be performed using a usual dryer, electric furnace, or the like other than air drying.

After the above-mentioned treatment, the surface of the usual tool is coated with the plasticizer. It can be confirmed whether or not the surface of the tool is coated with the plasticizer by comparison of the external appearance by visual observation, various measurements, etc. However, for example, it is preferred to determine that the surface of the tool is coated with the plasticizer when the deposition area is 5% or less, preferably 0% after performing the procedure up to copper sulfate plating in the method of Example 2 mentioned below. In the case where the surface of the tool is not coated with the plasticizer, the deposition area after copper sulfate plating does not fall within the above-mentioned range.

As a preferred embodiment of the tool of the present invention, for example, the following tools are exemplified.

<Usual Tool>

-   Electricity conducting part: SUS, copper -   Insulation part: soft vinyl chloride sol coating (containing dioctyl     phthalate as a plasticizer)

<Tool of the Present Invention>

The usual tool is immersed in dioctyl phthalate (stock solution), which is the plasticizer of the same type as contained in vinyl chloride, for 10 to 30 seconds. Subsequently, the usual tool is dried at 140 to 200° C. for 5 to 30 minutes to form a coating film of the plasticizer on the vinyl chloride sol on the surface of the usual tool, and then, the unnecessary plasticizer on the electricity conducting part is removed by a degreasing treatment, whereby the tool of the present invention is obtained.

The thus obtained tool of the present invention can be used for plating a resin molded body because even if a treatment such as etching, catalyst impartation, or plating is performed, plating deposition on the tool itself does not occur. The plating of the resin molded body may be any of electroplating, electroless plating, and a combination of these. Further, the type of the plating liquid is also not particularly limited; however, for example, in the case of electroless plating, electroless nickel plating, electroless copper plating, and the like can be exemplified, and in the case of electroplating, copper sulfate plating, nickel electroplating, chromium electroplating, and the like can be exemplified. Further, the resin molded body is not particularly limited; however, for example, molded bodies of ABS, PC/ABS, and the like can be exemplified. Further, as the conditions for the plating of the resin molded body, conventional plating conditions can be used except that the tool of the present invention is used as the tool.

In particular, it is preferred to use the tool of the present invention in so-called plating free from chromic acid etching, in which an etching liquid containing a permanganate as a main component, ozone or the like is used in place of using an etching liquid containing chromic acid in etching of the resin molded body. In the case where the usual tool is used as the tool to be used in such plating free from chromic acid etching, plating deposition on the tool occurs heavily, and the exchange of the tool is needed; however, in the case where the tool of the present invention is used, plating deposition on the tool does not occur.

EXAMPLES

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is by no means limited to these examples

Example 1 Production of Tool

A tool (electricity conducting part: copper (basic skeleton), SUS (branch skeleton)) coated with a general-purpose soft vinyl chloride sol (manufactured by MARUISHI KASEIHIN K.K., Product No. G-2330 black, containing dioctyl phthalate as a plasticizer) was immersed in a plasticizer shown in Table 1 for 20 seconds, and thereafter fired at a temperature shown in Table 1 for 20 minutes, and then, the unnecessary plasticizer on the electricity conducting part was removed by a degreasing treatment, whereby the tool of the present invention was produced.

TABLE 1 Firing Plasticizer temperature Tool A None — Tool B dioctyl phthalate 220° C. Tool C dioctyl phthalate 200° C. Tool D dioctyl phthalate 180° C. Tool E dioctyl phthalate 160° C. Tool F trioctyl trimellitate 160° C. Tool G tricresyl phosphate 160° C. Tool H tributyl acetylcitrate 160° C. Tool I dioctyl phthalate 160° C. tributyl acetylcitrate Tool J tricresyl phosphate 160° C. tributyl acetylcitrate

In the tool B, the plasticizer was volatilized by firing, and the external appearance thereof was the same as that of the tool A which was not treated with a plasticizer. The external appearances of the tools C to J were different from that of the tool A which was not treated with a plasticizer.

Example 2 Plating Test

To each of the tools A to J produced in Example 1, a flat plate (100 mm×50 mm×3 mm) of an ABS resin (CYCOLAC 3001M, manufactured by UMG ABS, Ltd.) to serve as a material to be plated was attached, and plating was performed under the conditions shown in Table 2. The deposition on the tool after electroless nickel plating and after copper sulfate plating was evaluated by the following method. The results are shown in Table 3.

TABLE 2 Liquid composition Treatment conditions Treatment step Component Concentration Temperature Time Degreasing ENILEX WE* 10 ml/L 50° C. 10 min sulfuric acid 20 ml/L Etching potassium permanganate 2 g/L 68° C. 15 min sulfuric acid 200 ml/L Neutralization ENILEX RD* 10 ml/L 25° C.  1 min reduction hydrochloric acid 50 ml/L Conditioner D-POP CDV* 10 ml/L 25° C.  1 min Catalyzer CT-580* 10 ml/L 35° C.  4 min hydrochloric acid 200 ml/L Accelerator hydrochloric acid 100 ml/L 35° C.  4 min Electroless nickel ENILEX NI-100AM* 140 ml/L 35° C.  5 min plating ENILEX NI-100BM* 140 ml/L Copper sulfate copper sulfate 225 g/L 25° C. 30 min plating sulfuric acid 55 g/L   3 A/dm² chlorine 60 ppm CU-BRITE EP-30A* 1 ml/L CU-BRITE EP-30B* 0.3 ml/L CU-BRITE EP-30C* 4 ml/L

 A sufficient water washing step is included between the respective steps. *Trade name of JCU CORPORATION

<Evaluation Method for Deposition on Tool>

The area of the insulation coating part of the tool was assumed to be 100%, and the area in which plating deposition occurred was evaluated into the following five grades by visual observation.

-   (Evaluation): (deposition area) -   A: 0% -   B: more than 0% and 5% or less -   C: more than 5% and 10% or less -   D: more than 10% and 50% or less -   E: more than 50%

TABLE 3 After After electroless copper nickel sulfate Plasticizer plating plating Tool A None E E Tool B dioctyl phthalate D D (no coating) Tool C dioctyl phthalate C B Tool D dioctyl phthalate B A Tool E dioctyl phthalate A A Tool F trioctyl trimellitate B B Tool G tricresyl phosphate A A Tool H tributyl acetylcitrate B B Tool I dioctyl phthalate C B tributyl acetylcitrate Tool J tricresyl phosphate B B tributyl acetylcitrate

The plating deposition state of the material to be plated after electroless nickel plating and after copper sulfate plating was favorable regardless of the tool used. However, with respect to the tools, in the case of the tools A and B which were not coated with a plasticizer, plating deposition on the tool occurred heavily both after electroless nickel plating and after copper sulfate plating. On the other hand, in the case of the tools C to J coated with the plasticizer, plating deposition on the tool occurred less both after electroless nickel plating and after copper sulfate plating. Further, it was found that even if plating was deposited on the tool after electroless nickel plating, the plating did not extend and the deposition occurred less after copper sulfate plating.

The tool of the present invention can be favorably used in plating of a resin molded body. 

What is claimed is:
 1. A tool for plating a resin molded body, wherein a surface of a plating tool having an insulation coating part is coated with a plasticizer.
 2. The tool for plating a resin molded body according to claim 1, wherein the plasticizer contains at least one selected from the group consisting of ester compounds synthesized from an acid and an alcohol.
 3. The tool for plating a resin molded body according to claim 1, wherein the plasticizer contains at least one selected from the group consisting of phthalate esters, adipate esters, trimellitate esters, phosphate esters, citrate esters, sebacate esters, azelate esters, maleate esters, and benzoate esters.
 4. The tool for plating a resin molded body according to any one of claims 1 to 3, wherein the insulation coating part is formed from a thermoplastic resin.
 5. The tool for plating a resin molded body according to any one of claims 1 to 3, wherein the tool is used for plating free from chromic acid etching.
 6. A method for producing a tool for plating a resin molded body, comprising treating a surface of a plating tool having an insulation coating part with a plasticizer so as to coat the surface of the plating tool having an insulation coating part with the plasticizer.
 7. A method for plating a resin molded body, comprising using the tool for plating a resin molded body according to any one of claims 1 to 5 in plating of the resin molded body.
 8. The method for plating a resin molded body according to claim 7, wherein the plating of the resin molded body is plating free from chromic acid etching. 